The Ethernet physical layer is the physical layer component of the Ethernet family of computer network standards. The Ethernet physical layer evolved over a considerable time span and encompasses quite a few physical media interfaces and several magnitudes of speed. The speed ranges from 1 Mbit/s to 100 Gbit/s, while the physical medium can range from coaxial cable to twisted pair and optical fiber. In general, network protocol stack software will work similarly on all physical layers.
Power Over Ethernet (POE) is a standardized system to provide electrical power along with data on Ethernet cabling. This allows a single cable to provide both data connection and electrical power to such devices as network hubs or closed-circuit TV cameras. Unlike standards such as Universal Serial Bus (USB) that also powers devices over data cables, POE allows long cable lengths.